A significant portion of the American population is considered to be obese, with an even larger portion of this population considered to be overweight. Obesity is also considered to be a growing problem in other industrialized countries and in developing countries where large numbers of people have become accustomed to Western-influenced high-caloric diets. It has been estimated that obesity contributes to 50% of chronic diseases in Western societies and is responsible for approximately 70% of preventable deaths in the United States. Health care costs associated with obesity are substantial. As a result, the development of compositions to effect weight loss is the subject of significant commercial interest.
Approaches to weight control include appetite suppressants, reduced-caloric diets, exercise regimens, inhibition of dietary nutrient absorption (for example, lipids), surgical procedures and the like. A variety of compositions for weight control have been developed. Desired characteristics for such products include the lack of undesirable side effects, high efficacy, convenient dosage regimens, and low cost. Drugs developed to treat obesity may have undesirable side effects, may be available only under medical supervision, and may be relatively expensive. Other products such as those with high fiber content may require inconveniently large doses to be effective.
One method of inhibiting the absorption of dietary lipids is by inhibiting digestion and/or metabolism of these lipids via administration of a suitable non-absorbable material to bind or sequester the lipids. For example, U.S. Pat. No. 4,223,023, Furda, issued Sep. 16, 1980, describes the ingestion of chitosan to bind fatty acids and prevent their utilization. Similarly, U.S. Pat. No. 5,453,282, Kanauchi et al., issued Sep. 26, 1995, describes dietary lipid absorption-inhibiting agents comprising a mixture of chitosan and ascorbic acid or a salt thereof. However, the efficacy of chitosan in increasing fat excretion is relatively low, requiring impracticably large doses to be effective as a dietary weight-control supplement. (See, for example, Lengsfeld et al., Obesity Research, Vol. 7, Suppl. 1, November 1999). Certain fat-imbibing polymer particles are described in U.S. Pat. No. 4,432,968 Page et al., issued Feb. 21, 1984. Fat-binding polymers are also described in WO 99/34787, Mandeville et al., published Jul. 15, 1999. Similarly, U.S. Pat. No. 3,980,968, Ingleman et al., issued Sep. 14, 1976, describes certain solid network (i.e., crosslinked) polymers containing amino groups for binding bile acids. Solid crosslinked polyurethane polymers which form a gel in the presence of water and which are capable of binding cholesterol and lipids have been described as in U.S. Pat. No. 4,340,699, Grouiller, issued Jul. 20, 1982.
Another approach to inhibiting the digestion and/or metabolism of dietary lipids is to utilize compounds that inhibit the activity of certain enzymes necessary for digestion of lipids. Polymers which inhibit the action of pancreatic lipase are described in U.S. Pat. No. 3,923,976, Fields and Johnson, issued Dec. 2, 1975 and U.S. Pat. No. 4,211,765, Johnson and Fields, issued Jul. 8, 1980. However, the efficacy of these materials in inhibiting lipid digestion is also low, as measured by fat excretion.
Other lipase inhibitors can reduce the digestion of fat and oil, thereby causing the elimination of unabsorbed fat and oil through the feces. Examples of lipase inhibitors include tetrahydrolipstatin (orlistat; XENICAL®) described in U.S. Pat. No. 4,598,089, Hadvary et al., issued Jul. 1, 1986; lipase inhibitors including 2-amino-4H-3,1-benzoxazin-4-one and its derivatives described in WO 0040247 published Jul. 13, 2000; 2-oxy-4H-3,1-benzoxazin-4-ones and its derivatives described in WO 0040569, published Jul. 13, 2000; 2-thio-4H-3,1-benzoxazin-4-one and its derivatives described in WO 0153278, published Jul. 26, 2001; teasaponin described in Han et al., Int. J. Obes. Relat. Metab. Disord., Vol. 25, pp. 1459-1464, 2001; long-chain alpha-keto amides described in Chiou et al., Lipids, Vol. 36, pp. 535-542, 2001; extract of Nomame Herba described in Yamamoto et al., Int. J. Obes. Relat. Metab. Disord., Vol. 24, pp. 758-764, 2000; chiral alkylphosphonates described in Cavalier et al., Chem. Phys. Lipids, Vol. 100, pp. 3-31, 1999; chiral isomers of beta-lactone described in Tomoda et al., Biochem. Biophys. Res. Commun., Vol. 265, pp. 536-540, 1999; and Pluronic L-101 described in Comai et al., Int. J. Obes., Vol. 4, pp. 33-42, 1980.
However, anal leakage of undigested oil is an adverse side effect often observed in subjects treated with sufficiently large doses of lipase inhibitors to be effective in the treatment of obesity. Several approaches have been described to ameliorate this side effect. Combining a lipase inhibitor with substantial amounts of water-insoluble crude fiber to increase the inhibition of fat absorption is described in U.S. Pat. No. 5,447,953, Isler et al., issued Sep. 5, 1995. Combining a lipase inhibitor with certain poorly digestible, poorly fermentable hydrophilic, hydrocolloidal food grade thickeners, or emulsifiers to reduce anal leakage is described in WO 00/09122, Hug et al., published Feb. 24, 2000. Similarly, combining a lipase inhibitor with chitosan or a derivative or salt thereof to reduce anal leakage is described in U.S. Pat. No. 6,030,953, Bailly et al., issued Feb. 29, 2000. However, at convenient dosage levels, the efficacy of such materials in eliminating anal leakage is relatively low, as evidenced by significant levels of oily fur greasing in rodents.
As described above, the use of effective doses of agents that inhibit certain enzymes necessary for the digestion and absorption of fats and oils can lead to significant undesirable symptoms. Known materials that sequester or bind dietary lipids typically have low efficacy, requiring inconveniently large doses to be effective in the prevention or treatment of obesity, or in ameliorating the side effects associated with certain drugs, laxatives and fat-substitutes.
Accordingly, it would be desirable to develop a composition useful for treatments such as weight control that: (1) is suitable for ingestion; (2) has minimal undesirable side effects; (3) has high efficacy; (4) has convenient dosage regimens; and (5) is broadly applicable to various lipids, lipid substitutes, and other lipophilic substances.